The present disclosure relates generally to Forward Error Correction (FEC) in optical communication links.
Optical communication system performance is generally limited by OSNR (Optical Signal to Noise Ratio) in WDM (Wave Division Multiplexing) systems. OSNR increases proportionally to the transmitted line rate, to the distance (and to use of optical amplification). Forward error correction has been leveraged to improve optical system performance. FEC provides additional coded data to enable error checking and correction of the digital data by a receiving device. Since FEC is based on electronics, it has a significantly lower cost as compared to optical mitigation techniques and is commonly employed in WDM systems. ITU recommendation G.709 (“Interface for the Optical Transport Network (OTN))” is an example of a framing structure which includes an FEC block. Conventional implementations based on this standard apply a fixed FEC overhead on top of a fixed 10 Gb/s payload (OC192/STM64 or 10GE) to obtain 6.2 dB of OSNR gain using a Reed-Solomon code for forward error correction, for example.
Implementations which use different FEC codes may provide additional OSNR gain, however, they are still limited by the fixed FEC and payload frame structure.
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